There's a new study out suggesting that more pregnant women appear to be using marijuana, sometimes to soothe anxiety and morning sickness. According to one survey conducted between 2007 and 2012, 79 percent of women "reported perceiving little to no harm in prenatal [pot] use", the Kaiser team noted.

Researchers at Columbia University analyzed data from the annual National Survey on Drug Use and Health from 2002 through 2014 and found a 62 percent increase in pregnant people who reported using marijuana in the 30 days prior to taking the survey over that 12-year period.

Among this youngest group, use of pot during pregnancy rose from 12.5 percent in 2009 to almost 22 percent by 2016.

Media reports noted that the time span of the study coincides with increased marijuana legalization in California, and the US, and may be indicative of a continuing trend, as recreational legalization in California is scheduled to take effect on January 1.

"Because of the possibility of concurrent use of marijuana and other substances of abuse, the evidence of its direct association with preterm labor, fetal growth restriction, preterm birth, low birthweight and stillbirth is still debatable, though these adverse effects lean more towards an increased likelihood of occurrence", Yankey continued.

Why the trend? The growing acceptance of marijuana may be a driving factor, the researchers said.

Young and Goler did not condone the consumption of marijuana during pregnancy.

The study also reported an increase in pot usage among older pregnant women ages 25 to 34.

Despite the uncertainty of how the drug affects the body, California will legalize recreational marijuana for adults over the age of 21 beginning January 1.